<script src="js/jQuery.js"></script>
<script src="js/jquery.zoom.js"></script>
<script src="js/main.js"></script>
<script type="text/javascript">
    
    $('.zoom').zoom();
    console.log($('.zoom'));
    
    $(document).on('click', '.gallery img', function(){
        var source = $(this).attr('src');
        console.log(source);
        $('.showing').attr('src', source);
        $('.zoomImg').remove();
        $('.zoom').zoom();
    });
</script>